G. Rohlfs notes that this surname is of Greco-Byzantine origin and shows a distribution in various areas of Calabria: in the city of Catanzaro and its province —with a presence in Badolato, Cortale and the Crotone area— and in the province of Reggio Calabria, in localities such as Laureana and Palmi. Rohlfs also records its presence in the region of Campania and in Sicily, and compares it with the Greek surname Gulàs. He further warns that in Argentina the surname may lose its written accent, taking the form Gulla.

P. Durante agrees on the Greek origin of the surname and links it to the term guleòn, meaning "cavern", although he flags this etymology with reservations.